Field of the Invention
This disclosure relates to a braille display device. More particularly, the disclosure relates to an impact resistant display device that employs a modular construction.
Description of the Background Art
A braille display is an electromechanical device that connects to a peripheral device, such as a computer or a monitor, by way of a wired or wireless connection. Braille displays are used to convert text characters from the peripheral device into braille characters that can be perceived by a blind or low vision user. Computer software can be used to convert both text and visual images into braille characters that can be read by the user. Braille displays consist of a line of tactile cells. Typical displays include an array of 20, 40, or 80 tactile cells. Each individual cell corresponds to a single braille character consisting of six or eight tactile pins that move up and down in response to an instruction signal. Braille characters are generated by raising certain pins above and keeping others below a tactile surface. The tactile pins can be driven by mechanical, electromechanical, piezoelectric, pneumatic, or magnetic effects. When in the raised position, the pins extend above the tactile surface and can be felt by a user. The cells of the array together represent a line of text. After a line of text has been read the user, the display can be refreshed to allow for additional lines to be presented and read.
Although tactile pins can be driven in a number of different ways, it is well known in the art to drive the pins via piezoelectric reeds or other electromechanical drivers. The instruction signal for an 8 pin cell would include 8 inputs corresponding to an up or down instruction for each pin. These instructions would be provided as corresponding electrical inputs to the electromechanical driver. If piezoelectric reeds are used, the electrical inputs actuate the reeds to cause certain tactile pins to protrude above a tactile surface, thereby allowing a specific braille character to be displayed.
An example of braille display is disclosed by U.S. Pat. No. 6,417,821 to Becker et al. Becker discloses a tactual computer monitor with rows and columns of rectangular cells. Each cell includes four rows and two columns of movable pins that can be read by a blind person. The pins are driven by electromechanical impact drivers.
Another example is disclosed by U.S. Pat. No. 4,266,936 to Rose. Rose discloses a portable braille display unit that is the size of a conventional braille page. Each braille character is displayed by a braille cell module that includes spring actuated pins that are controlled by bimetallic latches. To display the braille characters, an electrical current applied to resistively heat selected bimetallic latches. In response, the bimetallic latches bend and disengage from the pin, allowing a compressive spring to move the pin upwardly through a surface plate to display a braille dot.
The braille cells of the type discussed above are not durable and tend to be fragile. This fragile construction results in the display's malfunctioning upon being dropped or impacted. In particular, impacts to known displays often result in the electromechanical elements becoming misaligned, which in turn, precludes the proper operation of the tactile pins. In some cases, the pins fail to extend above the tactile surface upon actuation, and they likewise fail to fully retract below the surface when disengaged. For this reason, most known display constructions are designed for static, desktop uses. In such environments, the display device is unlikely to encounter the type of impact that could result in a pin misalignment or malfunction. However, this is an increasing need in the art for portable braille displays. And portable braille displays often get jostled, bumped, or dropped in day to day use. This is especially true for blind or low vision users. Even when impacts do not result in a complete malfunction, they otherwise interfere with the strict tolerances that are required to provide an acceptable feel to the reader, as the misalignment of any components can be perceived as static to the blind or low vision user. Even in the absence of shocks and impacts, maintaining the precise positioning and alignment of tactile pins has proven to be very difficult with known display constructions.
Nor do the display designs of the background art lend themselves to ease of repair or maintenance. In particular, accessing the mechanical, electromechanical, or piezoelectric components of the cell is often very difficult, if not impossible. As a result, the failure of any one individual braille cell often requires the wholesale replacement of all the cells in the display. Alternatively, the failure of a single cell can result in the entire display device having to be replaced. The inability to service individual cells, or groups of cells, is problematic as contaminants that build up on the pins must be removed or the pins must be replaced upon excessive wear. Also, as noted above, pins are especially susceptible to damage upon encountering impacts or shocks.
Accordingly, there is a need in the art to improve the construction design of braille displays. And there is a particular need in the art for portable braille displays that are more durable and resistant to impacts. There is also a need for braille displays with modular constructions that allow the displays to be serviced and repaired.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this field that the identified improvements should be made nor would it have been obvious as to how to make the improvements if the need for such improvements had been perceived.